The development of integrated circuits in over 50 years can be described by Moore's Law. The driving force to the future integrated circuit industry and the system development shall be reduction of power consumption, that is, the technology node is not to increase the integration degree, but to take the increase of the performance-to-power-consumption ratio as a goal. As the power consumption of integrated circuits becomes an unneglectable problem, a “green” nanoscale device aimed at low power consumption design emerges. The theoretical limit of a subthreshold slope of a conventional MOSFET is 60 mV/dec due to the limitation of thermoelectric force. As the device size decreases, the threshold voltage of the device decreases and a static leakage current of the device deteriorates inevitably, leading to an increase of the static power consumption and thus the requirement of low power consumption design in the future can not be satisfied. A TFET (Tunneling FET) controls the position of the channel energy band by using a gate electrode, and an on-current is provided to the TFET by using a band-to-band tunneling. Such a carrier generation mechanism, which is different from that of the MOSFET, overcomes a restriction to the subthreshold characteristic due to the Fermi distribution of the carriers in the source end, and it can further reduce the subthreshold slope of the device, reduce the static leakage current of the device, and hence reduce the static power consumption of the device. However, due to a tunneling barrier, a low tunneling efficiency is always a problem that is difficult to be solved. Although the application of a narrow-forbidden-band semiconductor overcomes the problem regarding to the magnitude of the tunneling current, a resulting leakage current and an increase of the cost resulting from the new material become the barriers to its massive application.